1. Field of the Invention
The present invention relates to a rechargeable battery, and more particularly, the present invention relates to a rechargeable battery that includes a bare cell having an electrode assembly, a can and a cap assembly, and a protective circuit board electrically connected to the bare cell, and its fabrication method.
2. Description of the Related Art
Since a rechargeable battery is capable of being recharged several times and of realizing a size-reduction and a high capacity, it recently has been actively researched and developed. Among rechargeable batteries, Nickel-Metal Hydride (Ni-MH) batteries, Lithium (Li), and Lithium-ion (Li-ion) batteries have been broadly used.
A bare cell of these rechargeable batteries is fabricated by arranging an electrode assembly including a cathode, an anode and a separator inside a can, covering a top of the can with a cap assembly in which an electrolyte solution is injected into the can before or after covering, and then sealing the can.
A core pack is formed by selectively or associatively connecting a safety device, such as a Positive Temperature Coefficient (PCT) element, a thermal fuse, a Protective Circuit Module (PCM), or other battery components to the sealed bare cell. The exterior of the rechargeable battery is completed by arranging the core pack inside an additional resin case, or filling the gap between the bare cell and the PCM with a hot-melt resin, followed by covering or labeling with a thin exterior material.
The safety device or other components are connected to cathode and anode terminals of the bare cell by a conductive structure called a lead plate. The safety device breaks an electric current, when the battery temperature reaches a high level or the battery voltage is suddenly increased by an over-charge or over-discharge, so as to prevent the battery from breakdowns or fire.
FIGS. 1 and 2 are exploded plane views of one example of a method of fabricating a rechargeable battery.
FIG. 1 illustrates a bare cell 210 having an approximate rectangular shape, an insulation plate 220 on the right-hand side of the bare cell and a protective circuit board portion divided into 3 parts on the right-hand side of the insulation plate. FIG. 2 illustrates a battery assembly 200 when the above components of FIG. 1 are assembled, and upper and lower covers 241 and 243 are respectively arranged on the top and bottom of the battery assembly.
The bare cell 210 is fabricated by arranging an electrode assembly and an electrolyte inside a polygonal can, which has an approximate rectangular parallelepiped shape and an upper opening portion, and covering with a cap assembly which has a cap plate.
An electrode terminal 212 is placed on the cap assembly, which forms an upper surface of the bare cell, and is insulated from the cap plate. The cap plate is welded to the can so as to have the same electrical polarity. Accordingly, when attaching the protective circuit board portion to one side surface of the bare cell 210, the insulation plate 220 is placed for electrical insulation between the protective circuit board portion and the bare cell 210. The insulation plate 220 is made of a double-sided adhesive material so as to attach the protective circuit board portion to the bare cell 210.
The protective circuit board portion includes 3 parts. The protective circuit board portion is positioned on a side surface of the bare cell by arranging a base case 231, which is molded of a resin and is capable of receiving a protective circuit board, on the insulation plate, positioning the protective circuit board formed into a shape corresponding to that of the base case 231, and assembling a cover case 39 having a shape corresponding to the exposed exterior shape of the base case 231 and the protective circuit board positioned thereon.
The protective circuit board is formed by connecting a Protection Circuit Module (PCM) 237 and a PTC element 235 to a PCB substrate 239 and welding nickel plates acting as electrical terminals 232 and 233 to both sides thereof. The two electrical terminals 232 and 233 of the protective circuit board are respectively electrically connected to the electrode terminal 212 formed on the upper portion of the bare cell and a lower surface of the can forming the bare cell. An additional insulation material may be further attached to the electrical terminal 232 to be connected to the electrode terminal 212 for electrically insulating it from the cap plate.
Referring to FIG. 2, upper and lower covers 241 and 243 are respectively attached to the top and bottom of the rechargeable battery assembly 200 formed by assembling the above components of FIG. 1.
Although not shown in the drawings, the exterior of the rechargeable battery may be completed by covering the whole side surface of the core pack of the rechargeable battery with a resin thin film, or covering with a resin thin cover. Furthermore, the core pack may be packed in an additional exterior case in order for an external contact terminal to be exposed. The exterior materials including a covering material, resin cover, exterior case and the like may be applied with or without a label.
However, since every process as described above is performed manually or mechanically, time and cost for performing each process are consumed. Especially, the protective circuit board portion includes a plurality of components, so that great amounts of time and cost are required for assembling thereof.
Furthermore, generally, as the number of processes is increased, the risk of defects occurring in each process is increased.